1. Technical Field
The present invention relates to a navigation system which provides route information including information on an actual location of a vehicle using an in-vehicle device mounted on the vehicle and a portable terminal device carried by a passenger, the portable terminal device, and the in-vehicle device, and more particularly to a navigation system, a portable terminal device, and an in-vehicle device which can realize highly-precise navigation while preventing duplication in resources.
2. Description of the Related Art
Known car navigation systems calculate an actual location of a car using a Global Positioning System (GPS), a gyro, a vehicle-speed sensor, and the like, and combines and displays the actual location of the vehicle with map information of surrounding roads and buildings on a display.
In addition, as the performances of portable terminal devices such as portable telephones and personal digital assistants (PDA) is enhanced, navigation systems using GPS come to be implemented in the portable terminal devices.
Some have tried to construct a car navigation system by connecting the portable terminal device equipped with a navigation function to an in-vehicle device. For example, Japanese Patent Application No. 2002-48560 discloses a technology for acquiring map data via a portable telephone to use the map data for car navigation. Further, Japanese Application No. 2005-181262 discloses a technology for realizing navigation by connecting a portable telephone with a navigation function to a vehicle with no navigation function.